2^2 Gen. Roy’s Account of 
error as fmall as poflible, occuitations of fixed ftars fhould only 
be made ufe of, for obtaining conclufive determinations. 
In vicinal fituations, the next beft mode to angular mea- 
furement is no doubt that of marking, by means of well- 
regulated clocks, as was done in the South of France, the 
repeated inftantaneous explofion of light, obferved at ftations as 
far diftant to the eaftward and weftward of the place of explo- 
fion as the circumftances will permit in practice, thefe diftances 
having been for the purpofe accurately fettled by trigonome- 
trical operation. The preferable ftations for experiments of 
this fort will be pointed out in the conclufion to the prefent 
Memoir. 
Table 
